d-spacing of analyzed Pb nanospheres compared with published values for native Pb, Pb–oxides, and Pb–silicates

dhkl observed, Å

Pb cubic

PbO2 orthorhombic

PbO orthorhombic

Pb3O4 tetragonal

Pb3Si2O7 trigonal

Pb21(Si7O22)2Si4O13 hexagonal

*a0 = 4.97 Å

a0 = 4.9505 Å

a0 = 4.9858 Å

a0 = 5.8952 Å

a0 = 8.8118 Å

a0 = 10.1264 Å

a0 = 9.9244 Å

b0 = 5.9590 Å

b0 = 5.4930 Å

b0 = 8.8118 Å

b0 = 10.1264 Å

b0 = 9.9244 Å

c0 = 5.4626 Å

c0 = 4.7544 Å

c0 = 6.5639 Å

c0 = 38.6780 Å

c0 = 34.2357 Å

2.9795 (020)

2.9476 (200)

2.9034 (112)

2.9230 (300)

3.0371 (124)

2.83 n = 7 (SD = 0.03)

2.858 (111)

2.8649 (300)

2.7310 (002)

2.7465 (020)

2.7863 (310)

2.4929 (200)

2.4896 (120)

2.5216 (212)

2.44 n = 12 (SD = 0.07)

2.475 (020)

2.3952 (102)

2.3782 (021)

2.4437 (230)

2.4842 (223)

2.4746 (221)

2.0883 (041)

2.1196 (211)

2.0768 (330)

1.99 n = 5 (SD = 0.09)

2.021 (211)

2.0132 (022)

2.0460 (112)

2.0320 (411)

2.009 (321)

1.75 n = 6 (SD = 0.01)

1.750 (022)

1.7591 (212)

1.7974 (022)

1.7907 (412)

1.52 n = 1

1.565 (113)

1.5290 (132)

1.5146 (302)

1.5111 (350)

1.4407 (431)

An asterisk indicates calculation from d-spacing. n, number of measurements; SD, standard deviation of measurements. From all measurements, only five different sets of d-spacings were obtained (first column), and these indicate cubic crystallographic symmetry. In all other crystal structures for Pb–oxide and Pb–silicate, d-spacings much larger than 2.83 Å should be observed. Nanospheres shown in Fig. 2 E and F can be only indexed as cubic Pb.